cache#

Database-backed cache for Node.js.

Requirements#

A MongoDB-compatible database. Pass an existing database, as a NodeDK scaffold plugin does.

Install#

npm i @nodedk/cache

Usage#

var createCache = require('@nodedk/cache')

module.exports = async function example(db) {
  var cache = createCache({ db, expires: 3600 })
  await cache.set('user:1', { name: 'Ada' })
  return cache.get('user:1')
}

createCache({ db, expires, collection = 'cache' }) returns the cache synchronously. db is required; expires is the optional default lifetime in seconds. Without it, values do not expire by default.

Cache keys are stored as document _id values and use the database's built-in unique _id index.

Set expires to define a default lifetime in seconds:

var cache = createCache({
  db,
  expires: 3600
})

Use collection to override the default cache collection name:

var cache = createCache({
  db,
  collection: 'application-cache'
})

API#

cache.set(id, value, options = {})#

Stores a value under id and resolves to that value. A falsy ID resolves to null. options.expires accepts an absolute Date, or 0 to disable expiration for this value. All cache methods return promises.

await cache.set('user:1', {
  name: 'Ada'
})

Override the default expiration with a date:

var expires = new Date(Date.now() + 5 * 60 * 1000)

await cache.set('user:1', { name: 'Ada' }, { expires })

Set expires to 0 to store a value without expiration:

await cache.set('user:1', { name: 'Ada' }, { expires: 0 })

cache.get(id)#

var user = await cache.get('user:1')

get returns null when the key does not exist or has expired. Expired entries are removed when read.

Delete a value#

Set a value to null to delete it. The deleted value is returned, or null if the key did not exist.

var deleted = await cache.set('user:1', null)

cache.clear()#

var result = await cache.clear()

console.log(result.n)

clear returns the number of deleted entries as { n }.

cache.sweep()#

var result = await cache.sweep()

console.log(result.n)

sweep deletes all expired entries and returns the number deleted as { n }.

Created by Vidar Eldøy